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[Q] Sign of wavefunction in PIB

  1. Nov 21, 2008 #1
    Dear all,

    I have a question about the sign of Schrodinger equation in particle in a box.
    What's the meaning of the sign (like -, +) of wavefunction in particle in a box?
    Can anybody explain that?
    Thank you.
     
  2. jcsd
  3. Nov 21, 2008 #2

    malawi_glenn

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    WHAT sign? Clarify.
     
  4. Nov 21, 2008 #3
    If you draw the graph of wavefunction of PIB at any state n, the shape oscillates with - and + signs. What's the significance of it?
     
  5. Nov 21, 2008 #4

    malawi_glenn

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    You mean that the wave function attain both postive and negative values?

    What is the strange thing about that, what make you wanna ask this question?
     
  6. Nov 21, 2008 #5
    Why do you ask me like that?
    I'm just curious about what the + and - sign of wavefunction stand for.
    I know if there is a change of sign, at that point there is a node.
    But basically I want to know the meaning of the sign.
     
  7. Nov 21, 2008 #6

    malawi_glenn

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    Because sometimes one has thought a bit on why one asks the question, that one has an idea and so on.

    There is no meaning about the sign of the wavefunction. The wavefunction is interprented as to the be probability density amplitude, and amplidtudes can attain both positive, negative and Complex values. So there is nothing strange that wave function have some negative and some positive values.
     
  8. Nov 21, 2008 #7
    Then, how can you explain the sudden probability change in a node?
     
  9. Nov 21, 2008 #8

    malawi_glenn

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    define "sudden" change, I dont think that is a mathematical term..
     
  10. Nov 21, 2008 #9
    Ok for the state n=2 in PIB, in the middle of length(x=half lenth) there is a node which means no probability at the point. How do you explain no probability at the point?
     
  11. Nov 21, 2008 #10

    malawi_glenn

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    That the particle can't be found there of course. Why is that strange? Forget about classical pictures of particles and motion.

    However, the wave function is only EXAKT 0 for ONE point. Now recall from calculus the "length" of a point....
     
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